In the current debate on the role of increase soil carbon in addressing both climate change and food security, there is consensus that farmed lands have the higher potential provided the best management practices are implemented. In the Sahel where farms usually have few sparse old trees with declining soil fertility, there is an ongoing re-greening process with increases in tree cover for which there is still a dearth of quantified information on its impacts on soil properties. This research aimed at filling that gap. We sampled soil using a concentric zone design around individual trees of dominant species and at different soil depths (0–10, 10–30, 30–50 and 50–70 cm) in four Sahelian countries: Burkina Faso, Mali, Niger and Senegal. The results showed increase total carbon content of the top 0–10 cm soil, generally with high sand content (> 70%), ranged from 0.16 to 0.44% (mean 0.23%). Under trees it was a factor 1.04–1.47 higher than away from trees. Different tree species thrived in different ecological niches and had different impacts on soil properties, highlighting the need for site and species matching in restoration activities. These results suggest that increase vegetation cover in the Sahel is associated with an increase in soil total carbon and this trend is more pronounced on sandy soils.

中文翻译：

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农民田地中的再生树木增加了整个萨赫勒地区的土壤碳

在当前关于增加土壤碳在解决气候变化和粮食安全方面的作用的辩论中，人们一致认为，如果实施最佳管理实践，耕地具有更大的潜力。在萨赫勒地区，农场通常很少有稀疏的老树，土壤肥力不断下降，随着树木覆盖率的增加，正在进行重新绿化的过程，但仍然缺乏关于其对土壤特性影响的量化信息。这项研究旨在填补这一空白。我们在四个萨赫勒国家：布基纳法索、马里、尼日尔和塞内加尔，在不同土壤深度（0-10、10-30、30-50 和 50-70 厘米）的优势树种周围使用同心带设计对土壤进行采样. 结果表明，表层 0-10 cm 土壤的总碳含量增加，通常含沙量较高 (> 70%），范围从 0.16 到 0.44%（平均 0.23%）。在树下它比远离树高 1.04-1.47 倍。不同的树种在不同的生态位中茁壮成长，对土壤特性产生不同的影响，突出了恢复活动中场地和物种匹配的必要性。这些结果表明，萨赫勒地区植被覆盖的增加与土壤总碳的增加有关，这种趋势在沙质土壤上更为明显。